Microsoft criticised the agreement between Apple and Google as anti-competitive, though iOS devices nevertheless includes Microsoft's search engine Bing as an option, but not by default.

Apple has hosted Google as iOS' default search engine since the device was introduced in 2007. Apple also favours Google Maps in the mobile operating system over competing services like Microsoft's Bing Maps.

The FTC's investigation into Google is looking into the search and mobile giant's business practices, particularly focusing on whether Google could be abusing its position in the mobile advertising market to boost its revenue.

Details of the relationship between Apple and Google could be crucial in the FTC's ongoing investigation.

European authorities are also investigating Google's business practices in line with the United States. Europe's antitrust commissioner Joaquin Almunia told Reuters in January to expect to rule by the end of March, just over a fortnight from now.

If Google is found to be in violation of European antitrust laws, it could face a fine of up to 10 percent of its global annual turnover, could be in the region of $3--$4 billion (€2.3--€3.1 billion).